JP6156558B1 - Method for producing cellulose acylate - Google Patents

Abstract

A method for producing a highly transparent cellulose acylate is provided. A method for producing cellulose acylate comprising a step of acylating cellulose in the presence of sulfuric acid and an organic acid having an acid dissociation index pKa of -7 or more and 1 or less. [Selection figure] None

Description

  The present invention relates to a method for producing cellulose acylate.

Conventionally, various thermoplastic resins have been provided and used for various applications. For example, thermoplastic resins are used in various parts of home appliances, automobiles, office equipment, electronic electrical equipment, and the like.
In recent years, plant-derived resins have been used as thermoplastic resins, and cellulose acylate is one of conventionally known plant-derived resins.

  For example, Patent Document 1 discloses that “a method for producing a cellulose ester, wherein (a) a cellulose solution is formed by dissolving cellulose in a carboxylated ionic liquid, (b) the cellulose solution is converted into an acylating reagent. Preparing an acylated cellulose solution containing a cellulose ester by contacting with, (c) precipitating cellulose by contacting the acylated cellulose solution with a non-solvent to precipitate at least a portion of the cellulose ester. Preparing a slurry comprising an ester and the carboxylated ionic liquid; (d) separating at least a portion of the precipitated cellulose ester from the carboxylated ionic liquid to recover recovered cellulose ester and separated carboxylation ion And (e) at least a part of the separated carboxylated ionic liquid as an alkyl formate and at least a part of the separated carboxylated ionic liquid as an alkylamine formate ionic liquid. A method comprising contacting under conditions sufficient to convert. "

  Patent Document 1 discloses that “the contact in step (b) is performed in the presence of a catalyst” and “the catalyst is sulfuric acid, alkylsulfonic acid, arylsulfonic acid, functional ionic liquid, Lewis acid, and a mixture thereof. Is selected from the group consisting of ".

Special table 2010-518245 gazette

  An object of the present invention is to provide a method for producing a cellulose acylate having a higher thermal fluidity than the case of acylating cellulose in the presence of sulfuric acid alone as a catalyst.

  The above problem is solved by the following means.

The invention according to claim 1
Sulfuric, and in the presence of an acid dissociation exponent pKa of -7 to 1 inclusive organic acids, have a step of acylating the cellulose,
The organic acid is a method for producing cellulose acylate, which is at least one selected from the group consisting of alkylsulfonic acid, arylsulfonic acid, and fluorinated alkylcarboxylic acid .
The invention according to claim 2
The method for producing cellulose acylate according to claim 1, wherein the organic acid is at least one selected from the group consisting of methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoroacetic acid.
The invention according to claim 3
The method for producing cellulose acylate according to claim 1, wherein the organic acid is a fluorinated alkylcarboxylic acid.

The invention according to claim 4
The method for producing cellulose acylate according to any one of claims 1 to 3, further comprising a step of deacylating and depolymerizing the acylated cellulose in the presence of hydrochloric acid.

The invention according to claim 5
The cellulose acylate production method according to any one of claims 1 to 4, wherein the degree of polymerization of the cellulose before acylation is 100 or more and 350 or less.

The invention according to claim 6
The cellulose acylate according to any one of claims 1 to 5 , wherein a cellulose acylate having a degree of polymerization of 100 to 350, a degree of substitution of 2.1 to 2.6, and a molecular weight distribution of 2 to 5 is produced. It is a manufacturing method.

According to the first aspect of the present invention, there is provided a method for producing cellulose acylate having higher thermal fluidity than the case of acylating cellulose in the presence of sulfuric acid alone as a catalyst.
According to the invention according to claim 4 , 5 or 6 , there is provided a method for producing cellulose acylate having a low molecular weight and high thermal fluidity as compared with the case of acylating cellulose in the presence of sulfuric acid alone as a catalyst. The

  Embodiments that are examples of the present invention will be described below.

[Method for producing cellulose acylate]
The method for producing cellulose acylate according to the present embodiment includes a step of acylating cellulose in the presence of sulfuric acid and an organic acid having an acid dissociation index pKa of -7 or more and 1 or less (hereinafter also referred to as “specific organic acid”). (Hereinafter also referred to as “acylation step”).

  In the method for producing cellulose acylate according to the present embodiment, the production of cellulose acylate having high thermal fluidity is realized by including the above-described steps. The reason is estimated as follows.

  First, conventionally, when acylating cellulose, sulfuric acid is generally used as a catalyst (hereinafter also referred to as “acylation catalyst”). However, the thermal fluidity of the obtained cellulose acylate (acylated cellulose) may be lowered or the transparency may be lowered. This is because sulfuric acid, which is an acylation catalyst, hardly penetrates into the cellulose, and the acylation reaction gradually proceeds from the surface of the cellulose. That is, there is a difference in the reaction rate of acylation between the surface and inside of the cellulose, and the degree of substitution of the cellulose acylate obtained (substitution degree of acyl group) becomes heterogeneous (the distribution of substitution degree is widened). If the distribution of the substitution degree is widened, cellulose having a high substitution degree and a cellulose having a low substitution degree are mixed, and the presence of the cellulose having a low substitution degree causes a strong interaction due to the effect of hydrogen bonding, which causes a decrease in thermal fluidity.

  On the other hand, when a specific organic acid (an organic acid having an acid dissociation index pKa of -7 or more and 1 or less) is used together with sulfuric acid as an acylation catalyst, it is considered that sulfuric acid easily penetrates into the cellulose together with the specific organic acid. . For this reason, the acylation reaction easily proceeds on the surface and inside of the cellulose in an equally short time, that is, the difference in the reaction rate of acylation between the surface and inside of the cellulose is reduced. As a result, the degree of substitution (acyl group substitution degree) of the obtained cellulose acylate is homogenized (substitution degree distribution becomes narrow), and it becomes easy to obtain a cellulose acylate having high thermal fluidity.

  From the above, it is presumed that the cellulose acylate production method according to the present embodiment realizes the production of cellulose acylate with high thermal fluidity. And since this cellulose acylate is also highly transparent, when it uses for a resin molding, the transparency of the resin molding obtained will also become high.

It should be noted that when the amount of sulfuric acid is increased in order to suppress a decrease in thermal fluidity or transparency of the obtained cellulose acylate (inhomogeneous substitution degree of cellulose acylate), the molecular weight of cellulose is excessively increased. May decrease. Thus, it is difficult to obtain cellulose acylate having appropriate physical properties (substitution degree close to homogeneity and targeted molecular weight) only by controlling the amount of sulfuric acid.
However, in the method for producing cellulose acylate according to the present embodiment, the degree of substitution can be homogenized without increasing the amount of sulfuric acid, so that the appropriate physical properties (with a degree of substitution close to homogeneity and the targeted molecular weight). ) Manufacture of cellulose acylate is also realized.

  Hereinafter, the detail of the manufacturing method of the cellulose acylate which concerns on this embodiment is demonstrated.

(First embodiment)
The method for producing cellulose acylate according to the first embodiment is, for example,
A step of acylating cellulose in the presence of sulfuric acid and an organic acid (specific organic acid) having an acid dissociation index pKa of −7 or more and 1 or less (hereinafter also referred to as “first acylation step”);
A step of deacylating and depolymerizing acylated cellulose in the presence of hydrochloric acid (hereinafter also referred to as “first deacylation step”);
Have

In the method for producing cellulose acylate according to the first embodiment, cellulose acylate having a low molecular weight and high thermal fluidity is obtained. The reason is estimated as follows.
As described above, in the acylation step, when a specific organic acid is used together with sulfuric acid as an acylation catalyst, it is considered that sulfuric acid easily penetrates into the cellulose together with the specific organic acid. On the other hand, the soaked organic acid and sulfuric acid remain inside the cellulose even in the deacylation step. When deacylation (hydrolysis or saponification) and depolymerization are carried out in this state and in the presence of hydrochloric acid, it is considered that these reactions proceed in a homogeneous manner. As a result, the cellulose acylate has a degree of substitution that is less homogeneous and has a narrow molecular weight distribution. can get.

Therefore, it is speculated that the cellulose acylate production method according to the first embodiment can obtain a cellulose acylate having a low molecular weight and high thermal fluidity. The obtained cellulose acylate has a low molecular weight, a degree of substitution close to homogeneity, and a narrow molecular weight distribution, and therefore has a low melting temperature.
And this cellulose ester has high transparency with moldability (for example, injection moldability), and when used for a resin molded product, the transparency of the resulting resin molded product is also increased. Moreover, the strength of the obtained resin molded body is also ensured.

(First acylation step)
In the first acylation step, cellulose is acylated in the presence of an acylation catalyst (sulfuric acid and a specific organic acid (an organic acid having an acid dissociation index pKa of −7 to 1).
Specifically, in the first acylation step, for example, the cellulose is acylated while stirring in a state where the cellulose is immersed or dispersed in a solution containing an acylation catalyst, an acylating agent, and an acylating solvent. In addition, cellulose may be immersed or dispersed in a solution containing an acylation catalyst (or an acylation catalyst aqueous solution), an acylating agent, and an acylating solvent, or in a solution in which cellulose is immersed or dispersed in an acylating solvent, An acylation catalyst (or an acylation catalyst aqueous solution) and an acylating agent may be added.

The cellulose to be acylated is high molecular weight cellulose (for example, cellulose having a polymerization degree of 1000 or more and 10,000 or less). As the high molecular weight cellulose, for example, various raw material celluloses such as wood pulp (coniferous pulp, hardwood pulp) and cotton linter pulp are used. Commercially available cellulose may be used as the high molecular weight cellulose. Examples of commercially available high molecular weight cellulose include KC Flock W50, W100, W200, W300G, W400G, W-100F, W60MG, W-50GK, W-100GK, NDPT, NDPS, LNDP, NSPP manufactured by Nippon Paper Industries Co., Ltd. -HR etc. are mentioned.
In addition, the cellulose used as the object of acylation may also contain different components such as hemicellulose derived from the raw material (pulp). For this reason, in this specification, the term "cellulose" also means containing different components, such as hemicellulose.

  The cellulose to be acylated may be subjected to an activation treatment. The activation treatment is, for example, a method of treating cellulose using an activator containing water (a method of spraying an activator on cellulose, a method of immersing cellulose in an activator, or the like). The activator may use an acylating solvent. Specifically, as the activation treatment, 1) a method of mixing cellulose and water, filtering the cellulose, mixing cellulose and an acylating solvent, and filtering the cellulose, and 2) mixing water and cellulose Examples thereof include a method of mixing a liquid (for example, a mixed liquid having a water content of 0 to 50% by mass) and cellulose and filtering the cellulose.

In addition, the temperature of an activation process is 0 degreeC-100 degreeC (preferably 10 degreeC-40 degreeC), for example.
The time for the activation treatment (the total time when the treatment is performed twice) is, for example, 0.1 hours to 20 hours (preferably 1 hour to 15 hours).

As the acylation catalyst, sulfuric acid and a specific organic acid (an organic acid having an acid dissociation constant pKa of −7 to 1) are used.
The acid dissociation constant pKa of the specific organic acid is preferably -7 or more and 1 or less, and preferably -6.5 or more and -1 or less from the viewpoint of homogenization of the degree of substitution and narrow distribution of the molecular weight distribution.
Examples of the specific organic acid include alkyl sulfonic acids (for example, methanesulfonic acid, ethanesulfonic acid, 10-camphorsulfonic acid, 2-aminoethanesulfonic acid, 3-aminopropanesulfonic acid and the like having 1 to 10 carbon atoms). Alkylsulfonic acid),
Arylsulfonic acid (for example, aryl having 6 to 10 carbon atoms such as benzenesulfonic acid, p-toluenesulfonic acid, 4-ethylbenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid) Sulfonic acid), fluorinated alkyl carboxylic acids (for example, alkyl sulfonic acids having 1 to 4 carbon atoms such as trifluoroacetic acid, pentafluoropropionic acid, and heptafluorobutyric acid).

Among these, as the specific organic acid, methanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid are preferable from the viewpoints of homogenizing the degree of substitution and narrowing the molecular weight distribution.
In addition, a specific organic acid may be used individually by 1 type, and may be used together 2 or more types.

  Here, the acid dissociation constant pKa of the specific organic acid is measured by a potentiometric titration method using water as a solvent. Specifically, neutralization titration is performed with a strong base such as sodium hydroxide or potassium hydroxide, and the pKa is calculated by obtaining the dissociation constant of the specific organic acid from the titration curve.

The amount of sulfuric acid as the acylation catalyst is preferably 0.1% by mass or more and 15% by mass or less, and preferably 1% by mass or more and 10% by mass with respect to cellulose, from the viewpoints of homogenizing the degree of substitution and narrowing the molecular weight distribution. % Or less is more preferable.
The amount of the specific organic acid as the acylation catalyst is preferably 0.1% by mass or more and 15% by mass or less, preferably 1% by mass or more, in terms of mass ratio to cellulose from the viewpoint of homogenization of the degree of substitution and narrow distribution of molecular weight distribution. 10 mass% or less is more preferable.
Here, the mass ratio of sulfuric acid to the specific organic acid (sulfuric acid / specific organic acid) is preferably 5/95 or more and 95/5 or less from the viewpoint of homogenization of the degree of substitution and narrow distribution of the molecular weight distribution. 90 or more and 90/10 or less are more preferable.

Examples of the acylating agent include compounds having an acyl group. Specifically, as the acylating agent, an alkylcarboxylic acid anhydride (for example, an alkyl having 2 to 6 carbon atoms in a straight or branched chain such as acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, etc. Suitable examples include carboxylic acid anhydrides) and organic acid halides (eg, acetic acid chloride, propionic acid chloride, butyric acid chloride, etc.). However, alkylcarboxylic acid anhydride is usually used as the acylating agent.
The acylating agent is selected according to the type of cellulose acylate desired to be obtained by acylation. For example, when cellulose acetate is obtained, acetic anhydride is applied as an acylating agent. Further, when cellulose acetate propionate is obtained, two kinds of acetic anhydride and propionic anhydride are applied as acylating agents.
In addition, an acylating agent may be used individually by 1 type, and may be used together 2 or more types.

  The amount of acylating agent is selected according to the degree of substitution of cellulose acylate desired to be obtained by acylation. Usually, in the first acylation step, cellulose acylate having a substitution degree of 3 (cellulose triacylate) is often obtained. In this case, the amount of the acylating agent is preferably 3 times or more and 10 times or less, more preferably 4 times or more and 8 times or less, in terms of a molar ratio of cellulose to hydroxyl groups.

As the acylating solvent, an alkyl carboxylic acid (for example, a linear or branched alkyl carboxylic acid having 1 to 6 carbon atoms such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, and valeric acid) is preferably used. Can be mentioned.
Among these, from the viewpoints of homogenizing the degree of substitution and narrowing the molecular weight distribution, as the acylating solvent, formic acid and acetic acid are preferable, and acetic acid is particularly preferable.
In addition, an acylating agent may be used individually by 1 type, and may be used together 2 or more types.

  From the viewpoint of homogenization of the degree of substitution, the amount of acylated solvent is preferably from 5 times to 30 times, and more preferably from 10 times to 25 times in terms of mass ratio to cellulose.

  As the acylating solvent, water may be used in combination with the alkylcarboxylic acid. However, the amount of water is 10% by mass or less with respect to the alkylcarboxylic acid.

Suitable conditions for the first acylation step are, for example, as follows.
Temperature: For example, 18 ° C. or higher and 100 ° C. or lower (preferably 20 ° C. or higher and 80 ° C. or lower)
Time: For example, 0.5 hours or more and 20 hours or less (preferably 1 hour or more and 10 hours or less).

(First deacylation step)
In the first deacylation step, acylated cellulose (hereinafter also referred to as “primary cellulose acylate”) is deacylated and depolymerized in the presence of hydrochloric acid. In the first deacylation step, the degree of substitution of primary cellulose acylate is adjusted by deacylation (hydrolysis or saponification), and the molecular weight of primary cellulose acylate is reduced by depolymerization to achieve the desired substitution. This is a step of obtaining a cellulose acylate having a degree of polymerization and a degree of polymerization (hereinafter also referred to as “secondary cellulose acylate”).

  Specifically, in the first deacylation step, for example, an aqueous hydrochloric acid solution is added to the solution that has undergone the first acylation step (a solution containing a primary cellulose acylate, an acylation catalyst, an acylating agent, and an acylating solvent). Stir after addition. That is, from the viewpoint of productivity, the first acylation step and the first deacylation step are preferably performed continuously in the same container.

In addition, in order to deactivate the remaining acylating agent before adding the hydrochloric acid aqueous solution, water or a mixed solution containing water and at least one selected from an acylating solvent (alkylcarboxylic acid) and a neutralizing agent, etc. It is better to add a quencher to the solution.
Neutralizing agents are alkali metal compounds (hydroxides such as sodium hydroxide and potassium hydroxide; carbonates such as sodium carbonate and potassium carbonate; organic acid salts such as sodium acetate and potassium acetate), alkaline earth metal compounds Bases such as (hydroxides such as calcium hydroxide; carbonates such as calcium carbonate; organic acid salts such as calcium acetate).

  In the first deacylation step, the amount of hydrochloric acid is 10% by mass with respect to primary cellulose acylate (cellulose acylated in the first acylation step) from the viewpoint of homogenizing the degree of substitution and suppressing the spread of the molecular weight distribution. % To 200% by mass is preferable, and 30% to 150% by mass is more preferable.

Suitable conditions for the first deacylation step are selected according to the degree of substitution and the degree of polymerization of the secondary cellulose acylate to be obtained, and are as follows, for example.
Temperature: For example, 18 ° C. or higher and 100 ° C. or lower (preferably 20 ° C. or higher and 80 ° C. or lower)
Time: For example, 0.5 hours to 30 hours (preferably 1 hour to 25 hours).

The first deacylation step was obtained by, for example, precipitating and filtering primary cellulose acylate after the first acylation step (obtained by washing, drying, etc. as necessary), powder. Primary cellulose acylate may be used. Here, the precipitation of the primary cellulose acylate is carried out, for example, by mixing a solution containing the primary cellulose acylate and a large amount of water.
In this case, in the first deacylation step, powder is prepared in a solution containing hydrochloric acid and a deacylation solvent (the same solvent as the acylation solvent, specifically, an alkylcarboxylic acid or a mixed solvent of an alkylcarboxylic acid and water). The primary cellulose acylate is deacylated and depolymerized in a state where the primary cellulose acylate is dissolved. Note that powdery primary cellulose acylate may be dissolved in a solution containing hydrochloric acid and a solvent, or an aqueous hydrochloric acid solution may be added to a solution in which powdered primary cellulose acylate is dissolved in a solvent.

  After the first deacylation step, water is added to the solution containing the secondary cellulose acylate, the secondary cellulose acylate is precipitated, filtered, and dried to obtain the desired powdery cellulose acylate. .

In addition, after carrying out the step of neutralizing the filtered secondary cellulose acylate, the step of washing the neutralized secondary cellulose acylate with water, etc., it is dried to obtain the desired powdery cellulose acylate. It is good to get a rate.
Here, the neutralization treatment is, for example, alkyl carboxylic acid (for example, linear or branched alkyl carboxylic acid having 1 to 6 carbon atoms such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, etc. ) Metal salt (metal salt of periodic table group 1 element such as Na, periodic table group 2 element such as Ca, etc.).

(Second Embodiment)
In the method for producing cellulose acylate according to the second embodiment, for example, in the presence of sulfuric acid and an organic acid (specific organic acid) having an acid dissociation index pKa of -7 or more and 1 or less, the degree of polymerization is 100 or more and 350 or less. A step of acylating cellulose (hereinafter also referred to as “second acylation step”).

In the method for producing a cellulose acylate according to the second embodiment, the second acylation step is the same as the first acylation step of the first embodiment, except that cellulose having a degree of polymerization of 100 to 350 is acylated as cellulose. To implement.
For this reason, also in the manufacturing method of the cellulose acylate which concerns on 2nd Embodiment, the cellulose acylate which has the homogenized substitution degree, and is low molecular weight and high heat fluidity is obtained.

In addition, after a 2nd acylation process, water is added to the solution containing a cellulose acylate, cellulose acylate is deposited, it filters, It dries, and the target powdery cellulose acylate is obtained.
Moreover, after carrying out the step of neutralizing the filtered cellulose acylate, the step of washing the neutralized cellulose acylate with water, etc., and then drying to obtain the desired powdery cellulose acylate Is good.

  Here, in the method for producing a cellulose acylate according to the second embodiment, if necessary, in the presence of hydrochloric acid, cellulose having a high molecular weight, cellulose having a polymerization degree of 100 or more and 350 or less before the second acylation step. And the step of deacylating the acylated cellulose (hereinafter also referred to as “second deacylation step”) after the second acylation step, etc. Good.

(Depolymerization process)
The depolymerization step is a step in which high molecular weight cellulose is reduced in molecular weight by depolymerization to obtain cellulose having a target molecular weight (cellulose having a polymerization degree of 100 or more and 350 or less).
Specifically, in the depolymerization step, for example, the high molecular weight cellulose is stirred while being immersed or dispersed in a solution containing hydrochloric acid and a solvent (solvent such as water, formic acid, and acetic acid). Is depolymerized. Note that cellulose may be immersed or dispersed in a solution containing hydrochloric acid and a solvent (for example, an aqueous hydrochloric acid solution), or after immersing or dispersing cellulose in a solution containing a solvent, an aqueous hydrochloric acid solution may be added.

  The high molecular weight cellulose is, for example, cellulose having a polymerization degree of 1000 or more and 10,000 or less, and examples thereof include the cellulose described in the first acylation step of the first embodiment.

  In the depolymerization step, the amount of hydrochloric acid is preferably 10% by mass or more and 200% by mass or less, and more preferably 30% by mass or more and 150% by mass or less in terms of mass ratio with respect to high molecular weight cellulose from the viewpoint of suppressing the spread of the molecular weight distribution.

Suitable conditions for the depolymerization step are selected according to the degree of polymerization of the cellulose to be obtained, and are as follows, for example.
Temperature: For example, 18 ° C. or higher and 100 ° C. or lower (preferably 20 ° C. or higher and 80 ° C. or lower)
Time: For example, 0.5 hours to 30 hours (preferably 1 hour to 25 hours).

  After the depolymerization step, powdered cellulose is obtained which is obtained by precipitation and filtration (washing, drying, etc., if necessary) in a solution containing cellulose having a desired degree of polymerization.

(Second deacylation step)
The second deacylation step adjusts the degree of substitution of the cellulose acylated in the second acylation step (hereinafter also referred to as “primary cellulose acylate”) by deacylation (hydrolysis or saponification). This is a step of obtaining cellulose acylate having a substitution degree (hereinafter also referred to as “secondary cellulose acylate”).

  Specifically, in the second deacylation step, for example, the primary cellulose acylate is deacylated in a state where the primary cellulose acylate is dissolved in a solution containing hydrochloric acid and a deacylation solvent. Note that primary cellulose acylate may be dissolved in a solution containing hydrochloric acid and a solvent, or an aqueous hydrochloric acid solution may be added to a solution in which primary cellulose acylate is dissolved in a solvent.

  Here, the primary cellulose acylate precipitates and filters the primary cellulose acylate from the solution that has undergone the second acylation step (a solution containing the primary cellulose acylate, the acylation catalyst, the acylating agent, and the acylating solvent). The powdered primary cellulose acylate obtained (and obtained by carrying out washing, drying, etc., if necessary) is used.

  Examples of the deacylation solvent include the same solvent as the acylation solvent used in the second acylation step. That is, examples of the deacylation solvent include alkylcarboxylic acids or mixed solvents of alkylcarboxylic acids and water.

  In the second deacylation step, the amount of hydrochloric acid is 10% by mass or more and 200% by mass or less in terms of mass ratio to primary cellulose acylate (cellulose acylated in the second acylation step) from the viewpoint of homogenization of the degree of substitution. Preferably, 30 mass% or more and 150 mass% or less are more preferable.

Suitable conditions for the second deacylation step are selected according to the degree of substitution of the secondary cellulose acylate to be obtained, and are as follows, for example.
Temperature: For example, 18 ° C. or higher and 100 ° C. or lower (preferably 20 ° C. or higher and 80 ° C. or lower)
Time: For example, 0.5 hours to 30 hours (preferably 1 hour to 25 hours).

In the second deacylation step, for example, an aqueous hydrochloric acid solution is added to the solution that has undergone the second acylation step (a solution containing a primary cellulose acylate, an acylation catalyst, an acylating agent, and an acylating solvent). May be.
In this case, in order to deactivate the remaining acylating agent before adding the hydrochloric acid aqueous solution, water or a mixed solution containing water and at least one selected from an acylating solvent (alkylcarboxylic acid) and a neutralizing agent It is better to add a quenching agent such as
Neutralizing agents are alkali metal compounds (hydroxides such as sodium hydroxide and potassium hydroxide; carbonates such as sodium carbonate and potassium carbonate; organic acid salts such as sodium acetate and potassium acetate), alkaline earth metal compounds Bases such as (hydroxides such as calcium hydroxide; carbonates such as calcium carbonate; organic acid salts such as calcium acetate).

  After the second deacylation step, water is added to the solution containing the secondary cellulose acylate, the secondary cellulose acylate is precipitated, filtered, and dried to obtain the desired powdery cellulose acylate. .

  In addition, after carrying out the step of neutralizing the filtered secondary cellulose acylate, the step of washing the neutralized secondary cellulose acylate with water, etc., it is dried to obtain the desired powdery cellulose acylate. It is good to get a rate.

In the method for producing cellulose acylate according to the present embodiment described above, depending on the type of acylating agent, various methods such as cellulose monoacetate, cellulose diacetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, etc. Cellulose acylate is obtained.
The second acylation step may be performed while monitoring the degree of substitution by NMR (Nuclear Magnetic Resonance) or the like, and may be terminated when the target degree of substitution is reached. In this case, the second deacylation step is not necessary.

(Cellulose acylate)
Hereinafter, preferred characteristics of cellulose acylate produced by the method for producing cellulose acylate according to this embodiment (hereinafter also referred to as “cellulose acylate according to this embodiment”) will be described.

The cellulose acylate according to this embodiment is a cellulose acylate (particularly, cellulose diacetate) having a degree of polymerization of 100 to 350, a degree of substitution of 2.1 to 2.6, and a molecular weight distribution of 2 to 5. Good. Cellulose acylate having this property (particularly cellulose diacetate) has a low melting temperature and high thermal fluidity. And the cellulose ester which has a characteristic has high transparency with moldability (for example, injection moldability), and when it uses it for a resin molding, the transparency of the resin molding obtained will also become high. Moreover, the strength of the obtained resin molded body is also ensured.
However, the characteristics of the cellulose acylate according to the present embodiment are not limited to the above characteristics, and are selected according to the intended use of the cellulose acylate.

  The degree of polymerization of the cellulose acylate according to this embodiment is preferably from 100 to 350, and more preferably from 150 to 300, from the viewpoint of reducing the melting temperature (improving moldability) and improving the strength of the resulting resin composition. .

Here, the degree of polymerization is determined from the weight average molecular weight by the following procedure.
First, the weight average molecular weight of cellulose acylate is polystyrene in a gel permeation chromatography apparatus (GPC apparatus: HLC-8320GPC, column: TSKgel α-M, manufactured by Tosoh Corporation) using a dimethylacetamide / lithium chloride = 90/10 solution. Measure in conversion.
Next, the degree of polymerization of cellulose acylate is determined by dividing by the molecular weight of the structural unit of cellulose acylate. For example, when the substituent of cellulose acylate is an acetyl group, the structural unit molecular weight is 263 when the degree of substitution is 2.4, and 287 when the degree of substitution is 2.9.

  The degree of substitution of the cellulose acylate according to the present embodiment is preferably 2.1 or more and 2.6 or less from the viewpoint of reducing the melting temperature (improving moldability) and improving the strength of the resulting resin composition. More preferably, it is 2.5 or less.

Here, the degree of substitution is an index indicating the degree to which the hydroxyl group of cellulose is substituted with an acyl group. That is, the degree of substitution is an index indicating the degree of acylation of cellulose acylate. Specifically, the degree of substitution means an intramolecular average of the number of substitutions in which three hydroxyl groups in the D-glucopyranose unit of cellulose acylate are substituted with acyl groups.
Then, the degree of substitution is ^at H 1 -NMR (manufactured by JMN-ECA / JEOL RESONANCE Co.), measured from the area ratio of the cellulose-derived hydrogen and an acyl group derived peak.

  The molecular weight distribution of the cellulose acylate according to this embodiment is preferably 2 or more and 4 or less, and more preferably 2.5 or more and 3.5 or less, from the viewpoint of improving transparency and reducing melting temperature (improving moldability). .

Here, the molecular weight distribution is a ratio (Mw / Mn) between the weight average molecular weight Mw and the number average molecular weight Mn.
And the weight average molecular weight Mw and the number average molecular weight Mn use a dimethylacetamide / lithium chloride = 90/10 solution, and a gel permeation chromatography apparatus (GPC apparatus: manufactured by Tosoh Corporation, HLC-8320GPC, column: TSKgel α-M). In polystyrene conversion.

  The cellulose acylate according to this embodiment is used as a resin for forming a resin molded body.

[Resin composition]
Hereinafter, a resin composition using the cellulose acylate according to this embodiment (hereinafter, also referred to as “resin composition according to this embodiment”) will be described.

  The resin composition according to the present embodiment includes the cellulose acylate according to the present embodiment. The resin composition according to the present embodiment may include a plasticizer, other components, and the like as necessary.

  In addition, it is preferable that content of a plasticizer shall be the quantity from which the ratio of the cellulose acylate to the whole resin composition becomes the above-mentioned range. More specifically, the proportion of the plasticizer in the entire resin composition is preferably 15% by mass or less, more preferably 10% by mass or less, and still more preferably 5% by mass or less. When the ratio of the plasticizer is within the above range, the elastic modulus becomes higher and the heat resistance becomes higher. In addition, bleeding of the plasticizer is also suppressed.

(Plasticizer)
Examples of the plasticizer include adipic acid ester-containing compounds, polyether ester compounds, sebacic acid ester compounds, glycol ester compounds, acetate esters, dibasic acid ester compounds, phosphate ester compounds, phthalate ester compounds, camphor, citric acid. Examples include esters, stearates, metal soaps, polyols, polyalkylene oxides, and the like.
Among these, adipic acid ester-containing compounds and polyether ester compounds are preferable, and adipic acid ester-containing compounds are more preferable.

-Adipate-containing compound-
The adipic acid ester-containing compound (compound containing adipic acid ester) is a compound of adipic acid ester alone or a mixture of adipic acid ester and a component other than adipic acid ester (a compound different from adipic acid ester) Indicates. However, the adipic acid ester-containing compound may contain 50% by mass or more of the adipic acid ester with respect to all components.

  Examples of the adipic acid ester include adipic acid diester and adipic acid polyester. Specifically, an adipic acid diester represented by the following general formula (AE-1), an adipic acid polyester represented by the following general formula (AE-2), and the like can be given.

In General Formulas (AE-1) and (AE-2), R ^AE1 and R ^AE2 are each independently an alkyl group or a polyoxyalkyl group [— (C _x H _2X —O) _y —R ^A1 ] ( However, R ^A1 represents an alkyl group, x represents an integer of 1 to 10, and y represents an integer of 1 to 10.
R ^AE3 represents an alkylene group.
m1 represents an integer of 1 or more and 20 or less.
m2 represents an integer of 1 or more and 10 or less.

In general formulas (AE-1) and (AE-2), the alkyl group represented by R ^AE1 and R ^AE2 is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. . The alkyl group represented by R ^AE1 and R ^AE2 may be linear, branched or cyclic, but is preferably linear or branched.
In the general formulas (AE-1) and (AE-2), in the polyoxyalkyl group [— (C _x H _2X —O) _y —R ^A1 ] represented by R ^AE1 and R ^AE2 , the alkyl group represented by R ^A1 is An alkyl group having 1 to 6 carbon atoms is preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. The alkyl group represented by R ^A1 may be linear, branched or cyclic, but is preferably linear or branched.

In general formula (AE-2), the alkylene group represented by R ^AE3 is preferably an alkylene group having 1 to 6 carbon atoms, and more preferably an alkylene group having 1 to 4 carbon atoms. The alkylene group may be linear, branched or cyclic, but is preferably linear or branched.

  In general formulas (AE-1) and (AE-2), the group represented by each symbol may be substituted with a substituent. Examples of the substituent include an alkyl group, an aryl group, and a hydroxyl group.

  The molecular weight (or weight average molecular weight) of the adipic acid ester is preferably 200 or more and 5000 or less, and more preferably 300 or more and 2000 or less. The weight average molecular weight is a value measured according to the above-described method for measuring the weight average molecular weight of cellulose acylate.

  Hereinafter, although the specific example of an adipic acid ester containing compound is shown, it is not necessarily restricted to this.

-Polyetherester compound-
Specific examples of the polyetherester compound include a polyetherester compound represented by the general formula (EE).

In General Formula (EE), R ^EE1 and R ^EE2 each independently represent an alkylene group having 2 to 10 carbon atoms. ^AEE1 and ^AEE2 each independently represent an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 18 carbon atoms. m represents an integer of 1 or more.

In general formula (EE), as an alkylene group which ^REE1 represents, a ^C3-C10 alkylene group is preferable and a C3-C6 alkylene group is more preferable. The alkylene group represented by ^REE1 may be linear, branched, or cyclic, but is preferably linear.
When the number of carbon atoms of the alkylene group represented by ^REE1 is 3 or more, a decrease in heat fluidity of the resin composition is suppressed, and thermoplasticity is easily exhibited. When the alkylene group represented by ^REE1 has 10 or less carbon atoms or the alkylene group represented by ^REE1 is linear, the affinity with cellulose acylate is likely to increase. For this reason, when the alkylene group represented by ^REE1 is linear, and the carbon number is in the above range, the moldability of the resin composition is improved.
From these viewpoints, the alkylene group represented by ^REE1 is particularly preferably an n-hexylene group (— (CH ₂ ) ₆ —). That is, the polyether ester compound is preferably a compound representing an n-hexylene group (— (CH ₂ ) ₆ —) as R ^EE1 .

In general formula (EE), as an alkylene group which ^REE2 represents, a ^C3-C10 alkylene group is preferable and a C3-C6 alkylene group is more preferable. The alkylene group represented by ^REE2 may be linear, branched or cyclic, but is preferably linear.
When the number of carbon atoms of the alkylene group represented by ^REE2 is 3 or more, a decrease in heat fluidity of the resin composition is suppressed, and thermoplasticity is easily exhibited. When the alkylene group represented by ^REE2 has a carbon number of 10 or less or the alkylene group represented by ^REE2 is linear, the affinity with cellulose acylate is likely to increase. For this reason, when the alkylene group represented by ^REE2 is linear and the carbon number is in the above range, the moldability of the resin composition is improved.
From these viewpoints, the alkylene group represented by ^REE2 is particularly preferably an n-butylene group (— (CH ₂ ) ₄ —). That is, the polyether ester compound is preferably a compound representing an n-butylene group (— (CH ₂ ) ₄ —) as ^REE2 .

In the general formula ^(EE), the alkyl group represented by ^{A EE1,} and ^{A EE2} is an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 2 to 4 carbon atoms. A ^EE1, and alkyl group represented by A ^EE2 are linear, branched, and may be either cyclic, branched is preferred.
Aryl groups A ^EE1, and represented by A ^EE2 is an aryl group having 6 to 12 carbon atoms, a phenyl group, an unsubstituted aryl group such as a naphthyl group, or t- butyl phenyl, substituted phenyl such as hydroxyphenyl group Groups.
A ^EE1, and aralkyl group represented by ^{A EE2,} a group represented by -R A -Ph. R ^A represents a linear or branched alkylene group having 1 to 6 carbon atoms (preferably 2 to 4 carbon atoms). Ph represents an unsubstituted phenyl group or a substituted phenyl group substituted with a linear or branched alkyl group having 1 to 6 carbon atoms (preferably 2 to 6 carbon atoms). Specific examples of the aralkyl group include unsubstituted aralkyl groups such as benzyl group, phenylmethyl group (phenethyl group), phenylpropyl group, and phenylbutyl group, or substituted groups such as methylbenzyl group, dimethylbenzyl group, and methylphenethyl group. An aralkyl group is mentioned.

At least one of A ^EE1, and ^{A EE2} is preferably an aryl group or an aralkyl group. In other words, a polyether ester ^{compound, A EE1,} and preferably (preferably a phenyl group) an aryl group as at least one of ^{A EE2} is a compound represented or aralkyl ^{group, A EE1,} and aryl groups as both ^{A EE2} ( A compound that preferably represents a phenyl group) or an aralkyl group is preferred.

  Next, the characteristics of the polyetherester compound will be described.

The weight average molecular weight (Mw) of the polyetherester compound is preferably from 450 to 650, more preferably from 500 to 600.
When the weight average molecular weight (Mw) is 450 or more, bleeding (a phenomenon of precipitation) becomes difficult. When the weight average molecular weight (Mw) is 650 or less, the affinity with cellulose acylate is likely to increase. For this reason, when a weight average molecular weight (Mw) is made into the said range, the moldability of a resin composition will improve.
In addition, the weight average molecular weight (Mw) of a polyetherester compound is a value measured by a gel permeation chromatograph (GPC). Specifically, the molecular weight measurement by GPC is carried out with a chloroform solvent using a Tosoh Corporation HPLC1100 as a measuring apparatus, using a Tosoh column TSKgel GMHHR-M + TSKgel GMHHR-M (7.8 mm ID 30 cm). . The weight average molecular weight is calculated from the measurement result using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample.

The viscosity of the polyether ester compound at 25 ° C. is preferably 35 mPa · s or more and 50 mPa · s or less, and more preferably 40 mPa · s or more and 45 mPa · s or less.
When the viscosity is 35 mPa · s or more, dispersibility in cellulose acylate is easily improved. When the viscosity is 50 mPa · s or less, the anisotropy of the dispersion of the polyetherester compound hardly appears. For this reason, when a viscosity is made into the said range, the moldability of a resin composition will improve.
The viscosity is a value measured with an E-type viscometer.

The solubility parameter (SP value) of the polyether ester compound is preferably from 9.5 to 9.9, and more preferably from 9.6 to 9.8.
When the solubility parameter (SP value) is 9.5 or more and 9.9 or less, the dispersibility in cellulose acylate is easily improved.
The solubility parameter (SP value) is a value calculated by the method of Fedor. Specifically, the solubility parameter (SP value) is, for example, Polym. Eng. Sci. , Vol. 14, p. 147 (1974), the SP value is calculated by the following formula.
Formula: SP value = √ (Ev / v) = √ (ΣΔei / ΣΔvi)
(Wherein Ev: evaporation energy (cal / mol), v: molar volume (cm ³ / mol), Δei: evaporation energy of each atom or atomic group, Δvi: molar volume of each atom or atomic group)
The solubility parameter (SP value) employs (cal / cm ³ ) ^1/2 as a unit, but the unit is omitted in accordance with common practice and expressed in a dimensionless manner.

  Hereinafter, although the specific example of a polyetherester compound is shown, it is not necessarily restricted to this.

(Other ingredients)
Examples of other components include flame retardants, compatibilizers, antioxidants, mold release agents, light proofing agents, weathering agents, colorants, pigments, modifiers, anti-drip agents, antistatic agents, and hydrolysis inhibitors. , Fillers, reinforcing agents (glass fiber, carbon fiber, talc, clay, mica, glass flake, milled glass, glass beads, crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, etc.). The content of these components is preferably 0% by mass to 5% by mass with respect to the entire resin composition. Here, “0 mass%” means that other components are not included.

(Other resins)
The resin composition according to the present embodiment may contain a resin other than the cellulose acylate. However, it is preferable that other resins have an amount such that the ratio of cellulose acylate in the entire resin composition falls within the above-described range.
Examples of other resins include conventionally known thermoplastic resins, and specifically, polycarbonate resins; polypropylene resins; polyester resins; polyolefin resins; polyester carbonate resins; polyphenylene ether resins; Polyethersulfone resin; Polyarylene resin; Polyetherimide resin; Polyacetal resin; Polyvinyl acetal resin; Polyketone resin; Polyetherketone resin; Polyetheretherketone resin; Polyarylketone resin; Polyethernitrile resin; Imidazole resin; polyparabanic acid resin; selected from the group consisting of aromatic alkenyl compounds, methacrylic acid esters, acrylic acid esters, and vinyl cyanide compounds Vinyl-based polymer or copolymer resin obtained by polymerizing or copolymerizing two or more kinds of vinyl monomers; diene-aromatic alkenyl compound copolymer resin; vinyl cyanide-diene-aromatic alkenyl compound copolymer Polymer resin; aromatic alkenyl compound-diene-vinyl cyanide-N-phenylmaleimide copolymer resin; vinyl cyanide- (ethylene-diene-propylene (EPDM))-aromatic alkenyl compound copolymer resin; vinyl chloride resin Chlorinated vinyl chloride resin; and the like. These resins may be used alone or in combination of two or more.

(Production method of resin composition)
The resin composition according to the present embodiment is produced, for example, by melt-kneading a mixture containing at least cellulose acylate and, if necessary, a plasticizer and other components. In addition, the resin composition according to the present embodiment is produced, for example, by dissolving the above components in a solvent.
Examples of the melt-kneading means include known means, and specific examples include a twin screw extruder, a Henschel mixer, a Banbury mixer, a single screw extruder, a multi-screw extruder, and a kneader.
The temperature at the time of kneading may be determined according to the melting temperature of the cellulose acylate to be used. From the viewpoint of thermal decomposition and thermal fluidity, for example, 140 ° C. or higher and 240 ° C. or lower is preferable, and 160 ° C. or higher. 200 degrees C or less is more preferable.

[Resin molding]
Hereinafter, a resin molded body using the resin composition according to the present embodiment (hereinafter also referred to as “resin molded body according to the present embodiment”) will be described.

The resin molded body according to the present embodiment includes the resin composition according to the present embodiment. That is, the resin molded body according to the present embodiment is configured with the same composition as the resin composition according to the present embodiment.
Specifically, the resin molded body according to the present embodiment is obtained by molding the resin composition according to the present embodiment. As the molding method, for example, injection molding, extrusion molding, blow molding, hot press molding, calendar molding, coating molding, cast molding, dipping molding, vacuum molding, transfer molding, or the like may be applied.

The molding method of the resin molded body according to the present embodiment is preferably injection molding because it has a high degree of freedom in shape. About injection molding, a resin composition is heated and melted, poured into a mold, and solidified to obtain a molded body. You may shape | mold by injection compression molding.
The cylinder temperature for injection molding is, for example, 140 ° C. or higher and 240 ° C. or lower, preferably 150 ° C. or higher and 220 ° C. or lower, more preferably 160 ° C. or higher and 200 ° C. or lower. The mold temperature for injection molding is, for example, 30 ° C. or more and 120 ° C. or less, and more preferably 40 ° C. or more and 80 ° C. or less. The injection molding may be performed using a commercially available device such as NEX500 manufactured by Nissei Plastic Industry, NEX150 manufactured by Nissei Plastic Industry, NEX70000 manufactured by Nissei Plastic Industry, SE50D manufactured by Toshiba Machine.

  The resin molded body according to the present embodiment is suitably used for applications such as electronic / electrical equipment, office equipment, home appliances, automobile interior materials, engine covers, vehicle bodies, and containers. More specifically, casings for electronic / electrical equipment and home appliances; various parts of electronic / electrical equipment and home appliances; interior parts for automobiles; storage cases such as CD-ROM and DVD; tableware; beverage bottles; Wrap material; film; sheet;

  EXAMPLES The present invention will be described in further detail with reference to examples below, but the present invention is not limited to these examples. Note that “part” means “part by mass” unless otherwise specified.

<Preparation of cellulose acetate (Compound 1)>
(Activation process)
1 kg of cellulose (KC Flock W50 manufactured by Nippon Paper Industries Co., Ltd., polymerization degree = 1020) was immersed in 16 kg of ion exchange water for 12 hours. Thereafter, the swollen cellulose taken out by filtration was put into 15 kg of acetic acid, stirred for 3 hours, filtered, and the activated cellulose was taken out.

(Acylation step)
20 kg of acetic acid, 5 kg of acetic anhydride, 40 g of methanesulfonic acid (pKa = -1.9) and 40 g of concentrated sulfuric acid aqueous solution (sulfuric acid concentration = 96%) (sulfuric acid amount = 38.4 g) are added to the activated cellulose. Then, acylation treatment (triacetylation treatment) was performed while stirring and mixing at a temperature of 40 ° C. or lower. The fiber pieces disappeared after 1.5 hours, and acylation was completed. This produced cellulose triacetate.

(Deacetylation process)
Next, 600 g of ion-exchanged water is added to a solution containing acylated cellulose (cellulose triacetate) to inactivate the remaining acetic anhydride, and then 800 g of a 0.2 M aqueous hydrochloric acid solution is added and stirred and mixed. The temperature was raised to ° C. Thereby, depolymerization proceeded with deacylation of cellulose triacetate, and heating and stirring were stopped when the target molecular weight (degree of polymerization) was reached while monitoring the molecular weight by GPC. This produced cellulose diacetate.
Next, the solution was cooled to room temperature (25 ° C.) and then poured into 30 kg of ion exchange water to precipitate cellulose diacetate (deacetylated cellulose). And the taken-out cellulose diacetate was washed with water 2-3 times, and it advanced to the next neutralization process.

(Neutralization process)
Cellulose diacetate (deacetylated cellulose) was added to 1.5 kg of ion exchange water and 1 g of calcium acetate, and the mixture was stirred at room temperature (25 ° C.) for 12 hours. Thereafter, filtration, washing with water, and drying treatment were performed to prepare cellulose diacetate. Table 1 shows the substitution degree, polymerization degree, and molecular weight distribution of the obtained cellulose diacetate.

<Preparation of cellulose acetate (compounds 2 to 10)>
Except for the conditions shown in Table 1 (concentrated sulfuric acid aqueous solution, organic acid, concentrated sulfuric acid aqueous solution, treatment conditions), an activation treatment step, an acylation step, a deacetylation step, in the same manner as the cellulose derivative (Compound 1), The neutralization process was performed and the cellulose acetate (compounds 2-10) was prepared.

<Preparation of cellulose acetate (Comparative Compound 1)>
(Acylation step)
80 g of concentrated sulfuric acid aqueous solution (sulfuric acid concentration = 96%) (sulfuric acid amount = 76.8 g) is added to cellulose activated in the same manner as cellulose acetate (compound 1), and stirred and mixed at a temperature of 40 ° C. or lower. The acylation treatment was performed. It took 4 hours for the fiber pieces to disappear, and the acylation was completed. This produced cellulose triacetate.

(Deacetylation process)
Next, 600 g of ion-exchanged water is added to a solution containing acylated cellulose (cellulose triacetate) to inactivate the remaining acetic anhydride, and then 800 g of a 0.2 M aqueous hydrochloric acid solution is added and stirred and mixed. The temperature was raised to ° C. Thereby, depolymerization proceeded with deacylation of cellulose triacetate, and it took 5 hours to reach the target molecular weight (degree of polymerization), and the heating and stirring were stopped. This produced cellulose diacetate.
Next, the solution was cooled to room temperature (25 ° C.) and then poured into 30 kg of ion exchange water to precipitate cellulose diacetate (deacetylated cellulose). The taken-out cellulose diacetate was washed with water 2-3 times and proceeded to the next neutralization step.

(Neutralization process)
Cellulose diacetate (deacetylated cellulose) was added to 1.5 kg of ion exchange water and 1 g of calcium acetate, and the mixture was stirred at room temperature (25 ° C.) for 12 hours. Thereafter, filtration, water washing, and drying treatment were performed to prepare cellulose diacetate (Comparative Compound 1). Table 1 shows the substitution degree, polymerization degree, and molecular weight distribution of the obtained cellulose diacetate.

<Preparation of cellulose acetate (Compound 11)>
(Activation process)
1 kg of cellulose (KC Flock W50 manufactured by Nippon Paper Industries Co., Ltd., polymerization degree = 1020) was immersed in 16 kg of ion exchange water for 12 hours. Thereafter, the swollen cellulose taken out by filtration was put into 15 kg of acetic acid, stirred for 3 hours, filtered, and the activated cellulose was taken out.

(Depolymerization process)
The activated cellulose was charged with 20 kg of acetic acid and 800 g of a 0.2M hydrochloric acid aqueous solution, and the temperature was raised to 70 ° C. while stirring and mixing. As a result, depolymerization of cellulose was advanced, and the heating and stirring were stopped when the target molecular weight (degree of polymerization) was reached while monitoring the molecular weight by GPC.

(Acylation step)
The depolymerized cellulose is charged with 5 kg of acetic anhydride, 40 g of methanesulfonic acid (pKa = -1.9), and 40 g of concentrated sulfuric acid aqueous solution (96%) (sulfuric acid amount = 38.4 g) at a concentration of 40 ° C. or less. The acylation treatment was performed while stirring and mixing. While monitoring the degree of substitution by NMR, the stirring was stopped when the desired degree of substitution was reached. This produced cellulose diacetate.
Next, the solution was cooled to room temperature (25 ° C.) and then poured into 30 kg of ion exchange water to precipitate cellulose diacetate (deacetylated cellulose). And the taken-out cellulose diacetate was washed with water 2-3 times, and it advanced to the next neutralization process.

(Neutralization process)
Cellulose diacetate (deacetylated cellulose) was added to 1.5 kg of ion exchange water and 1 g of calcium acetate, and the mixture was stirred at room temperature (25 ° C.) for 12 hours. Thereafter, filtration, washing with water, and drying treatment were performed to prepare cellulose diacetate. Table 2 shows the substitution degree, polymerization degree, and molecular weight distribution of the obtained cellulose diacetate.

<Preparation of cellulose acetate (compounds 12 and 13)>
Except for the conditions shown in Table 2 (concentrated sulfuric acid aqueous solution, organic acid, concentrated sulfuric acid aqueous solution, treatment conditions), the activation treatment step, acylation step, deacetylation step, in the same manner as the cellulose derivative (compound 11), The neutralization process was performed and the cellulose acetate (compounds 12 and 13) was prepared.

<Preparation of cellulose acetate (Comparative Compound 2)>
(Depolymerization process)
20 kg of acetic acid and 800 g of 0.2M hydrochloric acid aqueous solution were added to cellulose activated by the same method as cellulose acetate (Compound 11), and the temperature was raised to 70 ° C. while stirring and mixing. As a result, depolymerization of cellulose was advanced, and the heating and stirring were stopped when the target molecular weight (degree of polymerization) was reached while monitoring the molecular weight by GPC.

(Acylation step)
The depolymerized cellulose was charged with 5 kg of acetic anhydride and 80 g of concentrated sulfuric acid aqueous solution (96%) (sulfuric acid amount = 76.8 g), and acylated while stirring and mixing at a concentration of 40 ° C. or lower. While monitoring the degree of substitution by NMR, the stirring was stopped when the desired degree of substitution was reached. This produced cellulose diacetate.
Next, the solution was cooled to room temperature (25 ° C.) and then poured into 30 kg of ion exchange water to precipitate cellulose diacetate (deacetylated cellulose). And the taken-out cellulose diacetate was washed with water 2-3 times, and it advanced to the next neutralization process.

(Neutralization process)
Cellulose diacetate (deacetylated cellulose) was added to 1.5 kg of ion exchange water and 1 g of calcium acetate, and the mixture was stirred at room temperature (25 ° C.) for 12 hours. Thereafter, filtration, washing with water, and drying treatment were performed to prepare cellulose diacetate. Table 2 shows the substitution degree, polymerization degree, and molecular weight distribution of the obtained cellulose diacetate.

<Preparation of cellulose acetate (Comparative Compound 3)>
Except for the conditions shown in Table 1 (concentrated sulfuric acid aqueous solution, organic acid, concentrated sulfuric acid aqueous solution, treatment conditions), an activation treatment step, an acylation step, a deacetylation step, in the same manner as the cellulose derivative (Compound 1), A neutralization step was performed to prepare cellulose acetate (Comparative Compound 3).

<Preparation of cellulose acetate (compound 14)>
(Activation process)
1 kg of cellulose (KC Flock W50 manufactured by Nippon Paper Industries Co., Ltd., polymerization degree = 1020) was immersed in 16 kg of ion exchange water for 12 hours. Thereafter, the swollen cellulose taken out by filtration was put into 15 kg of acetic acid, stirred for 3 hours, filtered, and the activated cellulose was taken out.

(Depolymerization process)
The activated cellulose was charged with 20 kg of acetic acid, 40 g of methanesulfonic acid (pKa = -1.9), and 800 g of a 0.2M aqueous hydrochloric acid solution, and the temperature was raised to 70 ° C. while stirring and mixing. As a result, depolymerization of cellulose was advanced, and the heating and stirring were stopped when the target molecular weight (degree of polymerization) was reached while monitoring the molecular weight by GPC.

(Acylation step)
The depolymerized cellulose was charged with 5 kg of acetic anhydride and 40 g of concentrated sulfuric acid aqueous solution (96%) (sulfuric acid amount = 38.4 g), and acylated while stirring and mixing at a concentration of 40 ° C. or lower. While monitoring the degree of substitution by NMR, the stirring was stopped when the desired degree of substitution was reached. This produced cellulose diacetate.
Next, the solution was cooled to room temperature (25 ° C.) and then poured into 30 kg of ion exchange water to precipitate cellulose diacetate (deacetylated cellulose). And the taken-out cellulose diacetate was washed with water 2-3 times, and it advanced to the next neutralization process.

(Neutralization process)
Cellulose diacetate (deacetylated cellulose) was added to 1.5 kg of ion exchange water and 1 g of calcium acetate, and the mixture was stirred at room temperature (25 ° C.) for 12 hours. Thereafter, filtration, washing with water, and drying treatment were performed to prepare cellulose diacetate. Table 2 shows the substitution degree, polymerization degree, and molecular weight distribution of the obtained cellulose diacetate.

<Preparation of cellulose acetate (compound 15)>
(Activation process)
1 kg of cellulose (KC Flock W50 manufactured by Nippon Paper Industries Co., Ltd., polymerization degree = 1020) was immersed in 16 kg of ion exchange water for 12 hours. Thereafter, the swollen cellulose taken out by filtration was put into 15 kg of acetic acid, stirred for 3 hours, filtered, and the activated cellulose was taken out.

(Depolymerization process)
The activated cellulose was charged with 20 kg of acetic acid and 800 g of a 0.2M hydrochloric acid aqueous solution, and the temperature was raised to 70 ° C. while stirring and mixing. As a result, depolymerization of cellulose was advanced, and the heating and stirring were stopped when the target molecular weight (degree of polymerization) was reached while monitoring the molecular weight by GPC. Next, after cooling the solution to room temperature (25 ° C.), it was poured into 30 kg of ion-exchanged water to precipitate cellulose. And the taken-out cellulose was washed with water 2-3 times and proceeded to the next acylation step.

(Acylation step)
20 kg of acetic acid, 5 kg of acetic anhydride, 40 g of methanesulfonic acid (pKa = -1.9), and 40 g of concentrated sulfuric acid aqueous solution (sulfuric acid concentration = 96%) are added to the depolymerized cellulose. An acylation treatment (triacetylation treatment) was performed while stirring and mixing at a temperature of 40 ° C. or lower. The fiber pieces disappeared after 1.5 hours, and acylation was completed. This produced cellulose triacetate.

(Deacetylation process)
Next, 600 g of ion-exchanged water is added to a solution containing acylated cellulose (cellulose triacetate) to inactivate the remaining acetic anhydride, and then 800 g of a 0.2 M aqueous hydrochloric acid solution is added and stirred and mixed. The temperature was raised to ° C. Thereby, depolymerization proceeded with deacylation of cellulose triacetate, and heating and stirring were stopped when the target molecular weight (degree of polymerization) was reached while monitoring the molecular weight by GPC. This produced cellulose diacetate.
Next, the solution was cooled to room temperature (25 ° C.) and then poured into 30 kg of ion exchange water to precipitate cellulose diacetate (deacetylated cellulose). And the taken-out cellulose diacetate was washed with water 2-3 times, and it advanced to the next neutralization process.

(Neutralization process)
Cellulose diacetate (deacetylated cellulose) was added to 1.5 kg of ion exchange water and 1 g of calcium acetate, and the mixture was stirred at room temperature (25 ° C.) for 12 hours. Thereafter, filtration, washing with water, and drying treatment were performed to prepare cellulose diacetate. Table 2 shows the substitution degree, polymerization degree, and molecular weight distribution of the obtained cellulose diacetate.

<Preparation of cellulose acetate (Compound 16)>
(Activation process)
1 kg of cellulose (KC Flock W50 manufactured by Nippon Paper Industries Co., Ltd., polymerization degree = 1020) was immersed in 16 kg of ion exchange water for 12 hours. Thereafter, the swollen cellulose taken out by filtration was put into 15 kg of acetic acid, stirred for 3 hours, filtered, and the activated cellulose was taken out.

(Depolymerization process)
The activated cellulose was charged with 20 kg of acetic acid, 40 g of methanesulfonic acid (pKa = -1.9), and 800 g of a 0.2M aqueous hydrochloric acid solution, and the temperature was raised to 70 ° C. while stirring and mixing. As a result, depolymerization of cellulose was advanced, and the heating and stirring were stopped when the target molecular weight (degree of polymerization) was reached while monitoring the molecular weight by GPC. Next, after cooling the solution to room temperature (25 ° C.), it was poured into 30 kg of ion-exchanged water to precipitate cellulose. And the taken-out cellulose was washed with water 2-3 times and proceeded to the next acylation step.

(Acylation step)
20 kg of acetic acid, 5 kg of acetic anhydride, 40 g of methanesulfonic acid (pKa = -1.9), and 40 g of concentrated sulfuric acid aqueous solution (sulfuric acid concentration = 96%) are added to the depolymerized cellulose. An acylation treatment (triacetylation treatment) was performed while stirring and mixing at a temperature of 40 ° C. or lower. The fiber pieces disappeared after 1.5 hours, and acylation was completed. This produced cellulose triacetate.

(Deacetylation process)
Next, 600 g of ion-exchanged water is added to a solution containing acylated cellulose (cellulose triacetate) to inactivate the remaining acetic anhydride, and then 800 g of a 0.2 M aqueous hydrochloric acid solution is added and stirred and mixed. The temperature was raised to ° C. Thereby, depolymerization proceeded with deacylation of cellulose triacetate, and heating and stirring were stopped when the target molecular weight (degree of polymerization) was reached while monitoring the molecular weight by GPC. This produced cellulose diacetate.
Next, the solution was cooled to room temperature (25 ° C.) and then poured into 30 kg of ion exchange water to precipitate cellulose diacetate (deacetylated cellulose). And the taken-out cellulose diacetate was washed with water 2-3 times, and it advanced to the next neutralization process.

(Neutralization process)
Cellulose diacetate (deacetylated cellulose) was added to 1.5 kg of ion exchange water and 1 g of calcium acetate, and the mixture was stirred at room temperature (25 ° C.) for 12 hours. Thereafter, filtration, washing with water, and drying treatment were performed to prepare cellulose diacetate. Table 2 shows the substitution degree, polymerization degree, and molecular weight distribution of the obtained cellulose diacetate.

The production conditions for each cellulose acetate are listed in Tables 1 and 2 below.
In Table 2, in the production conditions of compounds 15 to 16, the upper value of the column of concentration and mass of hydrochloric acid aqueous solution indicates the concentration and mass of the aqueous hydrochloric acid solution added in the depolymerization step, and the lower value is deacetylation. The concentration and mass of the hydrochloric acid aqueous solution are shown in the process. In the production conditions for compound 16, the upper value in the column of the mass of organic acid indicates the mass of the organic acid added in the depolymerization step, and the lower value indicates the mass of the organic acid added in the acylation step.

<Preparation of pellet>
Kneading was carried out with a biaxial kneading apparatus (TEX41SS, manufactured by Toshiba Machine Co., Ltd.) at the charging ratio and kneading temperature of cellulose acylate and plasticizer shown in Table 3 to obtain resin composition pellets.

In Table 3, the details of the types of plasticizers are as follows.
Adipic acid ester mixture A: Daihachi Chemical Industry Co., Ltd., Daifanity 101
Adipic acid ester mixture B: manufactured by Adeka, Adeka Sizer RS-107

<Injection molding>
Using the obtained pellets, an ISO multipurpose dumbbell test piece (test part length 100 mm, width 10 mm, thickness 4 mm) was measured with an injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd., PNX40) at the cylinder temperature and mold temperature shown in Table 4. ) Was produced.

<Bending elastic modulus>
About the obtained dumbbell test piece, the deflection temperature under a 1.8 MPa load condition was measured by the method based on ISO-75 using the universal testing apparatus (Shimadzu Corporation, autograph AG-XPlus). The results are shown in Table 4.

<Evaluation of thermal fluidity>
The heat fluidity of the pellets was measured for the melt volume rate (MVR) at a load of 10 kg and a temperature of 200 ° C. using a melt indexer (MI3, manufactured by Toyo Seiki Co., Ltd.). The results are shown in Table 4.

<Transparency>
The total light transmittance of the obtained dumbbell test piece was measured with a spectral haze meter “SH7000 (Nippon Denshoku Industries Co., Ltd.)” and evaluated for transparency. The results are shown in Table 4.

From the above results, it can be seen that in this example, a molded article having higher transparency than that of the comparative example was obtained. Thereby, it turns out that the transparency of "cellulose acetate" which is a resin component is high.
In addition, the pellets (resin compositions) using “cellulose acetate compounds 1 to 16” in this example have a low melting temperature, high moldability (injection moldability), and high strength (flexural modulus). It turns out that a molded object is obtained.

Claims (6)

Sulfuric, and in the presence of an acid dissociation exponent pKa of -7 to 1 inclusive organic acids, have a step of acylating the cellulose,
The method for producing cellulose acylate , wherein the organic acid is at least one selected from the group consisting of alkylsulfonic acid, arylsulfonic acid, and fluorinated alkylcarboxylic acid .   The method for producing cellulose acylate according to claim 1, wherein the organic acid is at least one selected from the group consisting of methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoroacetic acid.   The method for producing cellulose acylate according to claim 1, wherein the organic acid is a fluorinated alkylcarboxylic acid. The method for producing cellulose acylate according to any one of claims 1 to 3, further comprising a step of deacylating and depolymerizing the acylated cellulose in the presence of hydrochloric acid. The method for producing a cellulose acylate according to any one of claims 1 to 4, wherein a degree of polymerization of the cellulose before acylation is 100 or more and 350 or less. The cellulose acylate according to any one of claims 1 to 5 , wherein a cellulose acylate having a degree of polymerization of 100 to 350, a degree of substitution of 2.1 to 2.6, and a molecular weight distribution of 2 to 5 is produced. Manufacturing method.